Graphene is a two-dimensional form of crystalline carbon, either a single layer of carbon atoms forming a honeycomb (hexagonal) lattice or several coupled layers of this honeycomb structure.
Graphite, which is a carbon compound, has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets. A one atom thick layer of graphite is referred to “graphene”.
The properties of graphene are quite different from those of carbon nanotubes in which carbon atoms are connected with each other in the form of a cylinder.
Electrons pass through graphene at a velocity of 105 m/sec ( 1/3000 of light velocity). Such graphene is more suitable for being used as an electronic device than carbon nanotubes having both semiconductor properties and metal properties being used.
Further, graphene has lately attracted considerable attention because it has excellent electrical and mechanical characteristics.
As such, the range of applications of graphene will become forever wider in the future, and examples of applications thereof may include transparent flexible displays, ultrahigh-speed nano memory, next-generation solar cells, etc.
In particular, research has been done into manufacturing an electronic device using graphene. For example, research into integrating a silicon-based electronic device with a photonic device to provide functionality has yielded a graphene electronic device which is integrated with various devices such as a photonic device, a memory device and the like, thus providing more functionality. As is well known, graphene is usefully used as an electron device, but is problematic in that it is difficult to develop a photonic device (particularly in the visible region or ultraviolet region) using graphene.
In order to overcome such a problem, it is very important to fabricate a device in which various functional nanostructures are formed on monocrystalline graphene.